On the campaign trail during his mother's Senate bid, Mitt and Lenore strategize in a hotel room

Square jaw set, white mane swept back, George Romney stormed into the Lansing Civic Center one day in November 1970, spoiling for a fight. His wife Lenore had just lost an ill-advised campaign for the U.S. Senate. Her husband blamed disloyal Republicans--Michigan Governor William Milliken most of all. George said privately that Milliken had "weaseled and, frankly, destroyed my wife as a candidate." Now he grabbed a microphone and denounced the room at large, where GOP leaders had gathered in Milliken's honor.

Silence fell. George set his eyes on Joyce Braithwaite, a 30-something party activist and an intimate of Lenore's. He...